Advances in the Diagnosis and Control of Johne's Disease

Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne´s disease or paratuberculosis (PTB), an infectious chronic enteritis in domestic and wildlife ruminants with important welfare, economic and potential public health consequences. In domestic ruminants, MAP is a major health problem, resulting in intermittent diarrhea, loss of body condition and lower milk productivity. The disease is widely spread in both domestic and wild ruminant populations in almost all countries in the world. There are many factors potentially impeding control and eradication of Johne´s disease including: a lack of basic understanding of the immunopathogenesis of MAP infection, limitations of diagnostic tests to recognize the chronic stages of the infection, the effect of the genetic host susceptibility, and the limitations of current inactivated vaccines to prevent the disease. Additional obstacles are interference with tests to identify animals infected with other mycobacterial species, such as Mycobacterium bovis, the causal agent of bovine tuberculosis. MAP appears to survive pasteurization and could enter the human food chain through meat, dairy products and untreated water supplies. Meta-analysis has demonstrated that the association of MAP with Crohn´s disease (CD) in humans cannot be denied although a casual role has not yet been demonstrated. Addressing PTB control worldwide should be considered a proactive step in ensuring consumer confidence if a causal link is established between PTB and CD.

This Research Topic aims to explore novel technologies which may have the potential both to advance our understanding of the immunopathology of MAP infection and to improve current diagnostic and control strategies; including transcriptomics, metagenomics, genomics, proteomics, and lipidomics. In this Research Topic, we welcome papers on emerging MAP diagnostic and prognostic assays based on biomarkers, changes in microbiota of MAP-infected cattle, bacteriophage assays, ddPCR, and novel MAP specific antigens. Large scale standardized studies to assess the impact of these novel diagnostic approaches and their capacity to augment current test in naturally infected animals are also welcome. The use of genetic selection to improve animal health has emerged from recent advances in genomics and their application to epidemiological data. Resistance to PTB is a heritable trait in cattle and provides an additional tool by which the disease can be controlled.

Specifically, in this Research Topic, we will therefore be seeking to advance knowledge in relation to:

1- The development of reliable early-stage diagnostics;
2- Validation of biomarker-based tests on naturally infected ruminants in various stages of infection;
3- Identification and validation of genetic markers associated with resistance and disease progression;
4- Development of vaccines that prevent the infection and do not interfere with diagnosis of other mycobacterial infections;
5- Better understanding of the immunomodulation and immune evasion strategies of MAP.

We hope to attract an international collection of papers that address both national and international factors impacting on the control of Johne´s disease within both domestic and wildlife species. In doing so, this Research Topic will provide a forum which will generate a greater understanding of the disease and inform future control efforts through the design of more effective interventions to deal with PTB, to breed resistant animals, to decrease economic losses and to improve food safety. In addition, the tools and strategies described in this research topic could have a significant role in the prevention, diagnosis, and treatment of CD.